Moulds are widely distributing in nature. In addition to their useful characteristics, such as the production of antibiotics and enzymes, they can also cause harm to humans and animals; indirectly by rendering food unfit for consumption and directly by means of infections. The loss of food as a consequence of it becoming mouldy is estimated at 1% of the annual production. In addition to the economic loss as a consequence of rotting, a public health problem also arises as a result of food growing mouldy, specifically as a consequence of the production of mycotoxins. Even when food or the raw materials for this are slightly contaminated with mould, they can already contain mycotoxins. Because of their stability, mycotoxins of this type are not or are hardly inactivated during the production process of the foodstuff, so that it is possible for the mycotoxins to end up in the foodstuffs to be consumed. It is generally known that testing for the presence of mycotoxins in foodstuffs is a time-consuming process, if only because of the large number of mycotoxins which is known at present. For example, moulds belonging to the genus Alternaria produce ten different mycotoxins. Testing for the presence of mycotoxins is then also usually restricted to the detection of aflatoxin, a carcinogen which is produced, inter alia, by species of the genus Aspergillus. In view of the frequency with which moulds produce mycotoxins a check of foodstuffs should also be based on the presence of moulds.
Over the years a number of methods have been developed for the determination of moulds in foodstuffs. These methods can be subdivided into;
a) the culture method; PA1 b) the detection of heat-stable enzymes; PA1 c) the microscopic method; and PA1 d) the chemical methods.
The abovementioned methods all have a number of disadvantages, which are explained in more detail below.
Re a). When the "culture method" is used, samples are transferred to a suitable medium in which the mould can multiply. The degree to which it multiplies is a measure for the initial mould formation. The disadvantage of this method is, however, that only viable moulds can be detected. Therefore, it is usually not possible to determine with this method whether a foodstuff has been prepared from mouldy raw materials.
Re b). The method involving the "detection of heat-stable mould enzymes" runs into technical problems when testing foodstuffs, in view of the fact that such enzymes can also occur naturally in the foodstuff to be tested.
Re c). With the "microscopic method" foodstuffs are examined microscopically for the presence of mould mycelium. Usually the so called Howard Mould Count is used for this purpose. A disadvantage of this widely used method is its laborious nature and the wide variation in results.
Re d). With the "chemical methods" substances specific for moulds are determined, such as chitin or ergosterol. For the determination of chitin, a cell wall constituent of the mould, chitin is converted to glucosamine, which subsequently is determined, for example colorometrically. However, this method is complex. Moreover, glucosamines also arise in non-mouldy foodstuffs. Similar objections also apply in the case of ergosterol determination.
To summarize, it can be stated that all of the methods currently in use for the determination of moulds in foodstuffs and the like have significant shortcomings.